<template>
    <div>
        <router-link
            tag="div"
            to="/"
            class="header-abs"
            v-show="showAbs"
        >
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div
            class="header-fixed"
            v-show="!showAbs"
            :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>

<script>
   export default {
      name: "DetailHeader",
      data () {
         return {
            showAbs:true,
            opacityStyle:{
               opacity: 0/*设置景点详情的透明度*/
            }
         }
      },
      methods:{
         handleScroll () {
            const top=document.documentElement.scrollTop;/*获取与顶部的距离*/
            if (top > 60) {
               let opacity =top / 140;
               opacity = opacity > 1 ? 1 : opacity;
               this.opacityStyle = {opacity};
               this.showAbs = false
            } else {
               this.showAbs = true
            }
         }
      },
      activated () {/*页面被展示自动执行的函数钩子*/
            window.addEventListener('scroll',this.handleScroll)
      },
      deactivated() {/*在当前页面被替换或隐藏时自动执行*/
         window.removeEventListener('scroll',this.handleScroll)
      }
   }
</script>

<style lang="stylus" scoped>
    @import "../../assets/styles/varibles.styl"
  .header-abs
    position absolute
    left .2rem
    top .2rem
    width .8rem
    height .8rem
    border-radius .4rem
    line-height .8rem
    text-align center
    background rgba(0, 0, 0, .8)
    .header-abs-back
      color #fff
      font-size .4rem
  .header-fixed
    z-index 2
    position fixed
    top 0
    left 0
    right 0
    height $headerHeight
    line-height $headerHeight
    text-align center
    color #fff
    background $bgColor
    font-size .32rem
    .header-fixed-back
      position absolute
      top 0
      left 0
      width .64rem
      text-align center
      font-size .4rem
      color #fff
</style>